Kiwi birds fill an ecological niche like that of anteaters and echidnas. They probe for small invertebrates in their habitat and act as a predator to them. They fulfill the role of foraging for worms, grubs, and other small organisms. They help control the population of these organisms in New Zealand. The Kiwi themselves are a prey to mammals such as ferrets, dogs, cats, etc. They are both predator and prey in the ecosystem they live in.
Energy moves from the multiple producers that collect energy from the sun, up to the weta, then the kiwi takes the energy from the kiwi, and lastly, the kiwi is eaten by the cat. The energy collected is high at the bottom of the food pyramid and low at the top of the pyramid. In correlation, there is a large population of organisms at the bottom of the pyramid, but only a fraction at the top of the pyramid.